Field of the Invention
The present invention relates to a transmission system of a vehicle.
Discussion of the Background
As a related art, a motorcycle equipped with a transmission as a so-called AMT (automated manual transmission) that carries out gearshift operation by electric power is disclosed. Specifically, a power unit of the related art includes an engine, a starting clutch that transmits an engine driving force to the downstream side when the engine rotation speed becomes a predetermined value or higher, a change clutch on the downstream side of the starting clutch, and a stepped transmission having a main shaft to which the rotation of the change clutch is transmitted and a countershaft. A transmission mechanism of a so-called interlocking spindle type is employed in which the change clutch and the transmission are operated by a clutch lever and a master arm, respectively, provided on a single (the same) spindle. At the time of shift-down, when the spindle rotates in a shift-down direction, first the clutch lever pivots and the change clutch is disconnected. Then, the master arm pivots and the shift stage of the transmission is moved to the lower stage by one stage. Thereafter, the spindle rotates in such a direction as to return to the initial position and the clutch is connected.
In the case of the vehicle with the AMT, when the vehicle is powered off in the state in which the gear position is second or higher (in-gear state) in driving, the engine is started in the in-gear state at second or higher at the time of the next engine starting. At this time, in order to ensure sufficient starting torque in the starting, a transmission control system automatically carries out shift-down operation to neutral (or first) when the engine is started (or power supply is activated).
Here, in the case of a vehicle with the AMT including a system to operate the change clutch and the shift separately, even when starting operation (accelerator operation) or the like from the driver is made immediately after starting in the in-gear state at second or higher, starting in a state in which the torque is low can be prevented if starting control is not carried out and the change clutch is not connected until the transmission is shifted to neutral (or first). See Japanese Patent Laid-Open No. 2013-228079.